1. Field of the Invention
The present invention is broadly concerned with an improved screw section-barrel assembly forming a part of an elongated extruder, and which is particularly designed for the processing of starch-bearing or cellulosic materials in the production of alcohol therefrom. More particularly, it is concerned with such an assembly and screw section wherein the latter is provided with means on the periphery thereof for pushing the material outwardly against an adjacent cutting edge on the barrel during rotation of the screw section in order to effectively subdivide the material passing through the extruder so that maximum surface area is presented for cooking purposes.
2. Description of the Prior Art
The recent worldwide shortage of energy at a reasonable price has led to a plethora of proposals of alternate energy sources. For example, use of so called power alcohol derived from waste or agricultural products has been suggested, and in fact there is considerable activity in this area, particularly in the United States. Generally speaking, production of power alcohol from other grain or starch-bearing materials involves cooking the material followed by enzyme treatment thereof o convert the starch to sugars, and finally fermentation of the sugars to alcohol. While this process as broadly stated is extremely old, a number of investigators have proposed new methods and apparatus for maximizing alcohol production at minimum costs. For example, U.S. patent application Ser. No. 06/091,798 filed Nov. 6, 1979, now Patent No. 4,286,058, discloses a significant breakthrough in the area of alcohol production, inasmuch as a batch-continuous alcohol production process is disclosed which makes use of a modified extrusion cooker designed to effectively handle highly moisturized grain or other starch-bearing materials.
In order to maximize the production of alcohol from starch-bearing or cellulosic materials, it is desirable that these materials be subdivided to achieve the maximum possible surface area. This enhances both cooking and enzyme treatment. This need is particularly important in connection with extrusion processing of such materials during alcohol production, because of the relatively short residence time thereof in the extruder barrel, as compared with vat-type processes for example.
While more or less conventional extrusion apparatus can be used for alcohol production, there exists a real and heretofore unsatisfied need in the art for improved extrusion devices particularly designed for maximum subdivision of starting materials employed.